Ordering distance of surface nanofacets on vicinal 4H-SiC(0001)

After high-temperature H2 etching, vicinal SiC(0001) surfaces showed periodically ordered nanofacet structures consisting of pairs of (0001) and (112n). Here, we found that the characteristic ordering distance of approximately 10nm is independent of the vicinal angle (4 degrees -8 degrees off). However, fluctuation in the ordering distance is dependent on the vicinal angle. The 5.7 degrees off surface showed superior periodicity. The classical elastic theory of a surface predicted the characteristic (constant) ordering distance but not the fluctuation in ordering periodicity. By introducing "quantized step bunching" due to periodic surface energy, which is unique to polymorphic SiC, the fluctuation is described.